With the rapid popularization of the Internet, web-based applications are flourishing, and remote access is increasing massively. As a result, the security problems are noticeable. Netscape puts forward a Secure Socket Layer (SSL) protocol to solve the security problems that occur while the browser accesses the Internet resources. Later, the Internet Engineering Task Force (IETF) standardizes the protocol, and renames the protocol as Transport Layer Security Protocol (TLS).
The Virtual Private Network (VPN) based on the SSL/TLS technology uses the SSL/TLS to ensure security and reliability of the user's remote access network, and make the data transmission in the remote access network as secure as that in a private network. In the past, the SSL/TLS VPN device provides only assurance for web access security. But now, it supports security assurance for various applications, and becomes one of the indispensable security products.
Both parties involved in the SSL/TLS communication use the same key to export functions, and use the same PreMasterSecret key and the random number as parameters to calculate out all keys in the communication process. Because the random number is transmitted in the form of plain texts, the security of the PreMasterSecret key is most essential in the SSL/TLS communication process.
In the process of development, the applicant finds that the PreMasterSecret key in the existing SSL/TLS handshake protocol is generated and sent by the client in both parties involved in the SSL/TLS communication according to the private key of the server. The form of generating PreMasterSecret key is unitary, which restricts the use scope of the SSL/TLS protocol and hinders the development of the SSL/TLS protocol.